<template>
  <transition mode="out-in" v-on="on">
    <slot></slot>
  </transition>
</template>
<script lang="ts">
  import { defineComponent } from 'vue'
  import { addClass, removeClass } from '/@/utils/domUtils'

  export default defineComponent({
    name: 'CollapseTransition',
    setup() {
      return {
        on: {
          beforeEnter(el) {
            addClass(el, 'collapse-transition')
            if (!el.dataset) el.dataset = {}

            el.dataset.oldPaddingTop = el.style.paddingTop
            el.dataset.oldPaddingBottom = el.style.paddingBottom

            el.style.height = '0'
            el.style.paddingTop = 0
            el.style.paddingBottom = 0
          },

          enter(el) {
            el.dataset.oldOverflow = el.style.overflow
            if (el.scrollHeight !== 0) {
              el.style.height = el.scrollHeight + 'px'
              el.style.paddingTop = el.dataset.oldPaddingTop
              el.style.paddingBottom = el.dataset.oldPaddingBottom
            } else {
              el.style.height = ''
              el.style.paddingTop = el.dataset.oldPaddingTop
              el.style.paddingBottom = el.dataset.oldPaddingBottom
            }

            el.style.overflow = 'hidden'
          },

          afterEnter(el) {
            removeClass(el, 'collapse-transition')
            el.style.height = ''
            el.style.overflow = el.dataset.oldOverflow
          },

          beforeLeave(el) {
            if (!el.dataset) el.dataset = {}
            el.dataset.oldPaddingTop = el.style.paddingTop
            el.dataset.oldPaddingBottom = el.style.paddingBottom
            el.dataset.oldOverflow = el.style.overflow

            el.style.height = el.scrollHeight + 'px'
            el.style.overflow = 'hidden'
          },

          leave(el) {
            if (el.scrollHeight !== 0) {
              addClass(el, 'collapse-transition')
              el.style.height = 0
              el.style.paddingTop = 0
              el.style.paddingBottom = 0
            }
          },

          afterLeave(el) {
            removeClass(el, 'collapse-transition')
            el.style.height = ''
            el.style.overflow = el.dataset.oldOverflow
            el.style.paddingTop = el.dataset.oldPaddingTop
            el.style.paddingBottom = el.dataset.oldPaddingBottom
          },
        },
      }
    },
  })
</script>
